I suspect that you'd find the following:
* on the road, the KLR is a clear winner in most ways
* in the dirt, you'll be much more comfortable on a TW
I have a 47tooth sprocket on the back of my TW and I've messed around a bit in the carb to make it happier on the road.. that said, I have a ride that I've been taking somewhat regularly as of late: its 30 miles each way, all 55mph speed limits, every does 62 the whole way. I get passed a lot unless I'm pushing the bike fairly hard, and holding the thing at 55 makes your arms buzz a bit even at this distance. I won't dissuade you further from buying a TW: I think they're a blast, but 3hrs at 60mph may get uncomfortable.